Green Dust in Coolant Reservoir


Registered User
As we get closer to summer I went to check my coolant to find it dry even tho my tbirds temp has been fine but it has this greenish dust in it. Is it ok to fill up with this in there and if not what is it and how should I go about removing it? Thanks.
Looks like oil/exhaust residue. Propably blown head gasket, mine was the same when it blew. You should remove the tank and clean it, not sure about the best method, I have tried with a brush and soap and it works ok.

If it gets dirty again it must be the head gasket or timing cover gasket could also leak oil into coolant.